The Tor Browser / file revision

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

  * You can obtain one at http://mozilla.org/MPL/2.0/. */

 #ifndef mozilla_dom_DOMJSProxyHandler_h

 #define mozilla_dom_DOMJSProxyHandler_h

 #include "mozilla/Attributes.h"

 #include "mozilla/Likely.h"

 #include "jsapi.h"

 #include "jsproxy.h"

 #include "nsString.h"

 #define DOM_PROXY_OBJECT_SLOT js::PROXY_PRIVATE_SLOT

 namespace mozilla {

 namespace dom {

 class DOMClass;

 enum {

   JSPROXYSLOT_EXPANDO = 0

 };

 template<typename T> struct Prefable;

 // This variable exists solely to provide a unique address for use as an identifier.

 extern const char HandlerFamily;

 inline const void* ProxyFamily() { return &HandlerFamily; }

 inline bool IsDOMProxy(JSObject *obj)

 {

     const js::Class* clasp = js::GetObjectClass(obj);

     return clasp->isProxy() &&

            js::GetProxyHandler(obj)->family() == ProxyFamily();

 }

 class BaseDOMProxyHandler : public js::BaseProxyHandler

 {

 public:

   BaseDOMProxyHandler(const void* aProxyFamily)

     : js::BaseProxyHandler(aProxyFamily)

   {}

   // Implementations of traps that can be implemented in terms of

   // fundamental traps.

   bool enumerate(JSContext* cx, JS::Handle<JSObject*> proxy,

                  JS::AutoIdVector& props) MOZ_OVERRIDE;

   bool getPropertyDescriptor(JSContext* cx, JS::Handle<JSObject*> proxy,

                              JS::Handle<jsid> id,

                              JS::MutableHandle<JSPropertyDescriptor> desc) MOZ_OVERRIDE;

   bool getOwnPropertyDescriptor(JSContext* cx, JS::Handle<JSObject*> proxy,

                                 JS::Handle<jsid> id,

                                 JS::MutableHandle<JSPropertyDescriptor> desc) MOZ_OVERRIDE;

   bool watch(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,

              JS::Handle<JSObject*> callable) MOZ_OVERRIDE;

   bool unwatch(JSContext* cx, JS::Handle<JSObject*> proxy,

                JS::Handle<jsid> id) MOZ_OVERRIDE;

   virtual bool getOwnPropertyNames(JSContext* cx, JS::Handle<JSObject*> proxy,

                                    JS::AutoIdVector &props) MOZ_OVERRIDE;

   // We override keys() and implement it directly instead of using the

   // default implementation, which would getOwnPropertyNames and then

   // filter out the non-enumerable ones.  This avoids doing

   // unnecessary work during enumeration.

   virtual bool keys(JSContext* cx, JS::Handle<JSObject*> proxy,

                     JS::AutoIdVector &props) MOZ_OVERRIDE;

 protected:

   // Hook for subclasses to implement shared getOwnPropertyNames()/keys()

   // functionality.  The "flags" argument is either JSITER_OWNONLY (for keys())

   // or JSITER_OWNONLY | JSITER_HIDDEN (for getOwnPropertyNames()).

   virtual bool ownPropNames(JSContext* cx, JS::Handle<JSObject*> proxy,

                             unsigned flags,

                             JS::AutoIdVector& props) = 0;

   // Hook for subclasses to allow set() to ignore named props while other things

   // that look at property descriptors see them.  This is intentionally not

   // named getOwnPropertyDescriptor to avoid subclasses that override it hiding

   // our public getOwnPropertyDescriptor.

   virtual bool getOwnPropDescriptor(JSContext* cx,

                                     JS::Handle<JSObject*> proxy,

                                     JS::Handle<jsid> id,

                                     bool ignoreNamedProps,

                                     JS::MutableHandle<JSPropertyDescriptor> desc) = 0;

 };

 class DOMProxyHandler : public BaseDOMProxyHandler

 {

 public:

   DOMProxyHandler()

     : BaseDOMProxyHandler(ProxyFamily())

   {

   }

   bool preventExtensions(JSContext *cx, JS::Handle<JSObject*> proxy) MOZ_OVERRIDE;

   bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,

                       JS::MutableHandle<JSPropertyDescriptor> desc) MOZ_OVERRIDE

   {

     bool unused;

     return defineProperty(cx, proxy, id, desc, &unused);

   }

   virtual bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,

                               JS::MutableHandle<JSPropertyDescriptor> desc, bool* defined);

   bool set(JSContext *cx, JS::Handle<JSObject*> proxy, JS::Handle<JSObject*> receiver,

            JS::Handle<jsid> id, bool strict, JS::MutableHandle<JS::Value> vp) MOZ_OVERRIDE;

   bool delete_(JSContext* cx, JS::Handle<JSObject*> proxy,

                JS::Handle<jsid> id, bool* bp) MOZ_OVERRIDE;

   bool has(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id, bool* bp) MOZ_OVERRIDE;

   bool isExtensible(JSContext *cx, JS::Handle<JSObject*> proxy, bool *extensible) MOZ_OVERRIDE;

   /*

    * If assigning to proxy[id] hits a named setter with OverrideBuiltins or

    * an indexed setter, call it and set *done to true on success. Otherwise, set

    * *done to false.

    */

   virtual bool setCustom(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,

                          JS::MutableHandle<JS::Value> vp, bool *done);

   static JSObject* GetExpandoObject(JSObject* obj)

   {

     MOZ_ASSERT(IsDOMProxy(obj), "expected a DOM proxy object");

     JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);

     if (v.isObject()) {

       return &v.toObject();

     }

     if (v.isUndefined()) {

       return nullptr;

     }

     js::ExpandoAndGeneration* expandoAndGeneration =

       static_cast<js::ExpandoAndGeneration*>(v.toPrivate());

     v = expandoAndGeneration->expando;

     return v.isUndefined() ? nullptr : &v.toObject();

   }

   /* GetAndClearExpandoObject does not DROP or clear the preserving wrapper flag. */

   static JSObject* GetAndClearExpandoObject(JSObject* obj);

   static JSObject* EnsureExpandoObject(JSContext* cx,

                                        JS::Handle<JSObject*> obj);

 };

 inline DOMProxyHandler*

 GetDOMProxyHandler(JSObject* obj)

 {

   MOZ_ASSERT(IsDOMProxy(obj));

   return static_cast<DOMProxyHandler*>(js::GetProxyHandler(obj));

 }

 extern jsid s_length_id;

 int32_t IdToInt32(JSContext* cx, JS::Handle<jsid> id);

 // XXXbz this should really return uint32_t, with the maximum value

 // meaning "not an index"...

 inline int32_t

 GetArrayIndexFromId(JSContext* cx, JS::Handle<jsid> id)

 {

   if (MOZ_LIKELY(JSID_IS_INT(id))) {

     return JSID_TO_INT(id);

   }

   if (MOZ_LIKELY(id == s_length_id)) {

     return -1;

   }

   if (MOZ_LIKELY(JSID_IS_ATOM(id))) {

     JSAtom* atom = JSID_TO_ATOM(id);

     jschar s = *js::GetAtomChars(atom);

     if (MOZ_LIKELY((unsigned)s >= 'a' && (unsigned)s <= 'z'))

       return -1;

     uint32_t i;

     JSLinearString* str = js::AtomToLinearString(JSID_TO_ATOM(id));

     return js::StringIsArrayIndex(str, &i) ? i : -1;

   }

   return IdToInt32(cx, id);

 }

 inline bool

 IsArrayIndex(int32_t index)

 {

   return index >= 0;

 }

 inline void

 FillPropertyDescriptor(JS::MutableHandle<JSPropertyDescriptor> desc,

                        JSObject* obj, bool readonly, bool enumerable = true)

 {

   desc.object().set(obj);

   desc.setAttributes((readonly ? JSPROP_READONLY : 0) |

                      (enumerable ? JSPROP_ENUMERATE : 0));

   desc.setGetter(nullptr);

   desc.setSetter(nullptr);

 }

 inline void

 FillPropertyDescriptor(JS::MutableHandle<JSPropertyDescriptor> desc,

                        JSObject* obj, JS::Value v,

                        bool readonly, bool enumerable = true)

 {

   desc.value().set(v);

   FillPropertyDescriptor(desc, obj, readonly, enumerable);

 }

 inline void

 FillPropertyDescriptor(JS::MutableHandle<JSPropertyDescriptor> desc,

                        JSObject* obj, unsigned attributes, JS::Value v)

 {

   desc.object().set(obj);

   desc.value().set(v);

   desc.setAttributes(attributes);

   desc.setGetter(nullptr);

   desc.setSetter(nullptr);

 }

 } // namespace dom

 } // namespace mozilla

 #endif /* mozilla_dom_DOMProxyHandler_h */